The present invention relates to a device for regulating the voltage at which an automobile battery is charged by means of an alternator.
More particularly, the invention concerns a regulation device which includesxe2x80x94in addition to a regulator proper, which delivers excitation signals to the inductor of the alternatorxe2x80x94a management unit external to said regulator and to the alternator, which controls said regulator.
For producing such a regulation device, a structure of the type illustrated in FIG. 1 could be considered.
The regulator 1 is composed therein of a control circuit 2 and a power circuit 3, the latter amplifying the excitation signals delivered by the control circuit 2. The amplified excitation signals are applied to the inductor 4a of the alternator 4 (the rotor) in the form of a voltage Vex causing an excitation current Ies in said inductor 4a. 
The control circuit 2 is connected, by means of a wired connection 6, to a computer 5xe2x80x94for example that of the engine controlxe2x80x94which constitutes the external management unit of the device.
With such a device, the regulation function is activated by the signal transmitted to the control circuit 2 by the computer 5xe2x80x94via the connection 6. This signal is for example a signal of the type referred to as pulse width modulation or PWM.
The control circuit 2 is then activated and transmits a pre-excitation signal to the power circuit 3. The alternator 4 is consequently magnetised, so that the rotation of the alternator generates a phase signal (a voltage at the terminals of one of the windings).
As soon as the control circuit 2 has detected this phase signal, the pre-excitation signal is transformed into an excitation signal in order to regulate the battery voltage.
However, such a structure is not fully satisfactory.
The connection 2 may be subjected to electromagnetic interference caused by equipment internal or external to the vehicle (a radio telephone for example). Such interference is liable to produce, at the terminals of the connection 6, overvoltages which may activate the control circuit 2 and, consequently, cause a pre-excitation current discharging the battery when the vehicle is stopped. It will be noted in particular that the discharge current may then be greater than 50 mA.
One aim of the invention is to mitigate this drawback and to propose a regulation device of the type which makes it possible to achieve the triggering of the regulator in normal mode and in degraded mode and offers good immunity against electromagnetic interference.
The recommended solution consists of magnetising the alternator circuit by means of an excitation current fixed by the control signal delivered by the external management unit, this control unit directly controlling the power stage of the regulator when the alternator is stopped.
According to one aspect of the present invention there is provided a device for regulating the voltage at which an automobile battery is charged by an alternator, including on the one hand a control circuit which comprises means for controlling the excitation of the inductor of the alternator as a function of the charging voltage, as well as means for detecting the start of rotation of the alternator, and on the other hand a power circuit which includes means for amplifying the excitation signals which are transmitted to it by the control circuit, said regulation device including an external management unit connected to the control circuit in order to transmit to it different regulation parameters, the power circuit also being connected to the external management unit and having means enabling it to generate by itself an excitation signal when the management unit delivers a control signal, the control circuit being adapted to be activated to emit an excitation signal only when the start of rotation of the alternator is detected.
This device is advantageously supplemented by the following different characteristics taken alone or in all their possible combinations:
the power circuit includes logic means which are connected to the means of detecting the start of rotation of the alternator, as well as to the external management unit, and which generate an excitation signal, by means of the amplification means, only when the external management unit delivers a control signal and no start of rotation of the alternator is detected;
the means of detecting the start of rotation of the alternator comprise a circuit for detecting the appearance of a voltage between two phases of the alternator;
the circuit for detecting this phase signal includes a signal detector which generates a high-level signal when the voltage which corresponds to this phase signal is greater than a given threshold, a timing device which receives the signal output from this detector and which is reset to zero when this signal is at its high level, a logic inverter whose input is connected to the output of the timing device and whose output is connected to a computer in the control circuit;
the power circuit includes a logic inverter which receives the signal emitted by the external management unit, and a logic NOR gate which receives the output of this logic inverter, as well as that of the logic inverter of the detection circuit;
the power circuit also includes a logic OR gate which receives as an input the output of said logic NOR gate, as well as the excitation control signal generated by the computer of the control circuit;
the control circuit and the power circuit includes means for regulating, when instructed by the external management unit, the voltage between two phases of the alternator;
the logic OR gate also receives as an input a signal generated by the means of regulating the voltage between two phases of the alternator;
the power circuit includes a second logic NOR gate whose output is sent as an input to the logic OR gate and which receives as an input a signal output from the computer of the detection circuit, as well as a signal output from the means detecting that the phases of the alternator have crossed one or more given voltage thresholds;
these means of detecting the crossing of a threshold or thresholds include a signal detector which generates a low-level signal when the phase voltages take peak values below a given threshold, a timing device which receives the signal output from this detector and which is reset to zero when this signal is at its high level, a logic inverter whose input is connected to the output of the timing device and whose output is transmitted to the second logic NOR gate.
According to a further aspect there is provided a device for regulating the voltage at which an automobile battery is charged by an alternator, including on the one hand a control circuit which comprises means for controlling the excitation of the inductor of the alternator as a function of the charging voltage, as well as means for detecting the start of rotation of the alternator, and on the other hand a power circuit which includes means for amplifying the excitation signals which are transmitted to it by the control circuit, said regulation device including an external management unit connected to the control circuit in order to transmit to it different regulation parameters, the power circuit also being connected to the external management unit and having means enabling it to generate by itself an excitation signal when the management unit delivers a control signal, the control circuit being adapted to be awakened to emit an excitation signal only when the start of rotation of the alternator is detected, wherein the power circuit includes logic means which are connected to the means of detecting the start of rotation of the alternator, as well as to the external management unit, and which generate an excitation signal, by means of the amplification means, only when the external management unit delivers a control signal and no start of rotation of the alternator is detected, wherein the means of detecting the start of rotation of the alternator comprise a circuit for detecting the appearance of a voltage between two phases of the alternator, and wherein the circuit for detecting this phase signal includes a signal detector which generates a high-level signal when the voltage which corresponds to this phase signal is greater than a given threshold, a timing device which receives the signal output from this detector and which is reset to zero when this signal is at its high level, a logic inverter whose input is connected to the output of the timing device and whose output is connected to a computer in the control circuit.
According to yet another aspect there is provided a device for regulating the voltage at which an automobile battery is charged by an alternator, including on the one hand a control circuit which comprises means for controlling the excitation of the inductor of the alternator as a function of the charging voltage, as well as means for detecting the start of rotation of the alternator, and on the other hand a power circuit which includes means for amplifying the excitation signals which are transmitted to it by the control circuit, said regulation device including an external management unit connected to the control circuit in order to transmit to it different regulation parameters, the power circuit also being connected to the external management unit and having means enabling it to generate by itself an excitation signal when the management unit delivers a control signal, the control circuit being adapted to be awakened to emit an excitation signal only when the start of rotation of the alternator is detected, wherein the power circuit includes logic means which are connected to the means of detecting the start of rotation of the alternator, as well as to the external management unit and which generate an excitation signal, by means of the amplification means, only when the external management unit delivers a control signal and no start of rotation of the alternator is detected, wherein the means of detecting the start of rotation of the alternator comprise a circuit for detecting the appearance of a voltage between two phases of the alternator, and wherein the circuit for detecting this phase signal includes a signal detector which generates a high-level signal when the voltage which corresponds to this phase signal is greater than a given threshold, a timing device which receives the signal output from this detector and which is reset to zero when this signal is at its high level, a logic inverter whose input is connected to the output of the timing device and whose output is connected to a computer in the control circuit, wherein the power circuit includes a logic inverter which receives the signal emitted by the external management unit, and a logic NOR gate which receives the output of this logic inverter, as well as that of the logic inverter of the detection circuit, wherein the power circuit also includes a logic OR gate which receives as an input the output of said logic NOR gate, as well as the excitation control signal generated by the computer of the control circuit, wherein the control circuit and the power circuit includes means for regulating, when instructed by the external management unit, the voltage between two phases of the alternator.